Fix sign-in and session activation

Successful sign-in requires a valid account, an available workspace, and browser storage for the session.

Try first#

1. Refresh the sign-in page and enter the account again.
2. Confirm that you use the correct YundaDesk address.
3. Check whether the browser blocks required cookies or local storage.
4. Try a private window to rule out an old session conflict.
5. Ask an administrator to confirm that the account and workspace are active.

If it still fails, record the time, browser, page address, and complete visible error. Never send a password, code, token, or browser cookie.

For repeated sign-outs, check system time, browser extensions that clear site data, and whether multiple environments use the same address.